In a polishing device, a substrate held on a substrate holding member is rotated, and the substrate is pressed against a rotating polishing pad such that a surface of the substrate is polished. In this instance, the substrate holding member is provided with a retaining ring that surrounds the substrate which is being polished in order to prevent the substrate from leaving a position for polishing. The retaining ring surrounds the substrate which is pressed against the polishing pad, and a bottom face of the retaining ring is pressed against the polishing pad. In this instance, a pressing force of a bottom face of the retaining ring applied to the polishing pad affects a polishing profile of a substrate edge portion.
However, even when the substrate is polished by setting the pressing force of the retaining ring applied to the polishing pad to a predetermined value, the substrate edge portion may not have a desired polishing profile due to a three-dimensional (3D) shape of the bottom face of the retaining ring. The reason is considered to be that a different pressing force of the retaining ring is applied to the polishing pad and the polishing pad has a different rebound state in a portion near the substrate edge portion due to the 3D shape of the bottom face of the retaining ring even when the pressing force of the retaining ring is set to a predetermined pressure.
In addition, when retaining rings are manufactured, a 3D shape of a bottom face varies for each of the retaining rings depending on a condition of precision during a machining process. Thus, when a retaining ring is replaced with a new retaining ring, a polishing profile formed before the replacement may not be reproduced. With regard to a shape of an inner circumferential surface of the retaining ring; it is generally known that change with time during use affects the polishing profile, in particular, the polishing profile in a portion near a substrate edge.
A scheme of completing a 3D shape of a bottom face of a retaining ring through a break-in of the retaining ring by polishing a dummy substrate using an actual machine, a scheme of previously processing a bottom face of a retaining ring into a 3D shape which is formed after completing a break-in by machining, and the like have been adopted as conventional schemes for solving the above-mentioned problem.
However, the conventional schemes have problems below. First, a processing accuracy of the retaining ring needs to be raised, and thus cost increases. In addition, when the break-in is performed, a rate of operation of an apparatus decreases, and costs of a dummy substrate, slurry, and the like are incurred. Further, in a semiconductor manufacturing site, a polishing condition may be changed according to a type of a product. However, strictly speaking, the 3D shape of the bottom face of the retaining ring is changed according to a type of process or a polishing condition. Therefore, in practice, it is difficult to control a shape in a rigorous manner.
It is desired to suppress deterioration in reproducibility of a polishing profile due to a variation or change with time of a shape of a retaining ring of a substrate holding member for each of retaining rings.
A polishing device of an embodiment includes a substrate holding member configured to press a substrate against a polishing pad and have a retaining ring surrounding the substrate pressed against the polishing pad, a sensor configured to measure a surface shape of the retaining ring, and a controller configured to determine a polishing condition of the substrate based on the surface shape of the retaining ring measured by the sensor. According to this configuration, a surface shape of a retainer ring is measured, and the polishing condition of the substrate is determined based on the measured surface shape, and thus it is possible to reduce influence by a variation or change with time of the surface shape of the retainer ring.
A polishing method of an embodiment includes a polishing process of polishing a substrate by relatively moving the substrate and a polishing pad in a state in which the substrate is surrounded by a retaining ring and pressed against the polishing pad, a measurement process of measuring a surface shape of the retaining ring, and a control process of determining a polishing condition in the polishing process based on the surface shape of the retaining ring measured in the measurement process, wherein in the polishing process, the substrate is polished according to the polishing condition determined in the control process.